package com.chengli.nio.recent.channel;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.junit.Test;

/**
 * <pre>
 * 一、通道（Channel）：用于源节点与目标节点的连接。在 Java NIO 中负责缓冲区中数据的传输。Channel 本身不存储数据，因此需要配合缓冲区进行传输。
 *
 * 二、通道的主要实现类
 * 	java.nio.channels.Channel 接口：
 * 		|--FileChannel
 * 		|--SocketChannel
 * 		|--ServerSocketChannel
 * 		|--DatagramChannel
 *
 * 三、获取通道
 *      1. Java 针对支持通道的类提供了 getChannel() 方法
 * 		        本地 IO：
 * 		            FileInputStream/FileOutputStream
 * 		            RandomAccessFile
 *
 * 		        网络IO：
 * 		            Socket
 * 		            ServerSocket
 * 	        	    DatagramSocket
 *
 *      2. 在 JDK 1.7 中的 NIO.2 针对各个通道提供了静态方法 open()
 *      3. 在 JDK 1.7 中的 NIO.2 的 Files 工具类的 newByteChannel()
 *
 * 四、通道之间的数据传输
 * 		transferFrom()
 * 		transferTo()
 *
 * 五、分散(Scatter)与聚集(Gather)
 * 		分散读取（Scattering Reads）：将通道中的数据分散到多个缓冲区中
 * 		聚集写入（Gathering Writes）：将多个缓冲区中的数据聚集到通道中
 *
 * 六、字符集：Charset
 * 		编码：字符串 -> 字节数组
 * 		解码：字节数组  -> 字符串
 * </pre>
 */
public class TestChannel {

    /**
     * 字符集
     */
    @Test
    public void test6() throws IOException {
        Charset cs1 = Charset.forName("GBK");
        /**获取编码器*/
        CharsetEncoder ce = cs1.newEncoder();
        /**获取解码器*/
        CharsetDecoder cd = cs1.newDecoder();
        CharBuffer cBuf = CharBuffer.allocate(1024);
        cBuf.put("尚硅谷威武！");
        cBuf.flip();
        /**编码*/
        ByteBuffer bBuf = ce.encode(cBuf);
        for (int i = 0; i < 12; i++) {
            System.out.println(bBuf.get());
        }
        /**解码*/
        bBuf.flip();
        CharBuffer cBuf2 = cd.decode(bBuf);
        System.out.println(cBuf2.toString());
        System.out.println("------------------------------------------------------");
        Charset cs2 = Charset.forName("GBK");
        bBuf.flip();
        CharBuffer cBuf3 = cs2.decode(bBuf);
        System.out.println(cBuf3.toString());
    }

    @Test
    public void test5() {
        Map<String, Charset> map = Charset.availableCharsets();
        Set<Entry<String, Charset>> set = map.entrySet();
        for (Entry<String, Charset> entry : set) {
            System.out.println(entry.getKey() + "=" + entry.getValue());
        }
    }

    /**
     * 分散和聚集
     */
    @Test
    public void test4() throws IOException {
        RandomAccessFile raf1 = new RandomAccessFile("1.txt", "rw");
        /**1. 获取通道*/
        FileChannel channel1 = raf1.getChannel();
        /**2. 分配指定大小的缓冲区*/
        ByteBuffer buf1 = ByteBuffer.allocate(100);
        ByteBuffer buf2 = ByteBuffer.allocate(1024);
        /**3. 分散读取*/
        ByteBuffer[] bufs = {buf1, buf2};
        channel1.read(bufs);
        for (ByteBuffer byteBuffer : bufs) {
            byteBuffer.flip();
        }
        System.out.println(new String(bufs[0].array(), 0, bufs[0].limit()));
        System.out.println("-----------------");
        System.out.println(new String(bufs[1].array(), 0, bufs[1].limit()));
        /**4. 聚集写入*/
        RandomAccessFile raf2 = new RandomAccessFile("2.txt", "rw");
        FileChannel channel2 = raf2.getChannel();
        channel2.write(bufs);
    }

    /**
     * 通道之间的数据传输(直接缓冲区)
     */
    @Test
    public void test3() throws IOException {
        FileChannel inChannel = FileChannel.open(Paths.get("d:/1.mkv"), StandardOpenOption.READ);
        FileChannel outChannel = FileChannel.open(Paths.get("d:/2.mkv"), StandardOpenOption.WRITE,
                StandardOpenOption.READ, StandardOpenOption.CREATE);
        /**inChannel.transferTo(0, inChannel.size(), outChannel);*/
        outChannel.transferFrom(inChannel, 0, inChannel.size());
        inChannel.close();
        outChannel.close();
    }

    /**
     * 使用直接缓冲区完成文件的复制(内存映射文件)
     */
    @Test
    public void test2() throws IOException {//2127-1902-1777
        long start = System.currentTimeMillis();
        FileChannel inChannel = FileChannel.open(Paths.get("d:/1.mkv"), StandardOpenOption.READ);
        FileChannel outChannel = FileChannel.open(Paths.get("d:/2.mkv"), StandardOpenOption.WRITE,
                StandardOpenOption.READ, StandardOpenOption.CREATE);
        /**内存映射文件*/
        MappedByteBuffer inMappedBuf = inChannel.map(MapMode.READ_ONLY, 0, inChannel.size());
        MappedByteBuffer outMappedBuf = outChannel.map(MapMode.READ_WRITE, 0, inChannel.size());
        /**直接对缓冲区进行数据的读写操作*/
        byte[] dst = new byte[inMappedBuf.limit()];
        inMappedBuf.get(dst);
        outMappedBuf.put(dst);
        inChannel.close();
        outChannel.close();
        long end = System.currentTimeMillis();
        System.out.println("耗费时间为：" + (end - start));
    }

    /**
     * 利用通道完成文件的复制（非直接缓冲区）
     */
    @Test
    public void test1() {
        long start = System.currentTimeMillis();

        FileInputStream fis = null;
        FileOutputStream fos = null;
        /**①获取通道*/
        FileChannel inChannel = null;
        FileChannel outChannel = null;
        try {
            fis = new FileInputStream("d:/1.mkv");
            fos = new FileOutputStream("d:/2.mkv");
            inChannel = fis.getChannel();
            outChannel = fos.getChannel();
            /**②分配指定大小的缓冲区*/
            ByteBuffer buf = ByteBuffer.allocate(1024);
            /**③将通道中的数据存入缓冲区中*/
            while (inChannel.read(buf) != -1) {
                buf.flip(); //切换读取数据的模式
                /**④将缓冲区中的数据写入通道中*/
                outChannel.write(buf);
                buf.clear(); //清空缓冲区
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (outChannel != null) {
                try {
                    outChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (inChannel != null) {
                try {
                    inChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        long end = System.currentTimeMillis();
        System.out.println("耗费时间为：" + (end - start));

    }
}
